U.S. Pat. No. 5,606,998 (Wahhoud et al.), issued on Mar. 4, 1997, corresponding to European Patent Publication EP 0,716,171 A2, discloses a weft detecting and stretching device for a jet weaving loom, wherein the weft insertion channel in the reed can be extended by one or more channel extension members and/or by intermediate inserts and by a telescoping feature, for accommodating various positions of the extension members, whereby the weft stretching and detecting device can accommodate different weft stretching characteristics. One embodiment of the known device has a weft stretching channel with its own and weft stop motion device and an extension channel also with its own weft stop motion device for detecting faulty weft threads. The other embodiment of the known device has only a weft insertion channel extension that is adjustable in its length and has its own weft stop motion device. The output signals of the weft stop motion devices are transmitted to the central loom control to stop the loom in response to a detection of a faulty weft thread. The stretching of the weft thread is accomplished by diverting the leading end of the weft thread out of a guide channel that is aligned with the weft insertion channel in the reed, into the weft stretching channel that is laterally displaced from the guide channel. By diverting the weft into the stretching channel with an air jet blowing the required stretching is accomplished.
The known apparatus is equipped with two weft stop motion devices in one embodiment. Further, an additional air jet nozzle is required if a modified stretching is intended in the guide channel.
German Patent DE 3,200,637 C2 (Dekker) discloses an air jet weaving loom with two waft stop motion devices, one of which is positioned in the weft insertion channel near the exit end of the channel and the other is positioned in a weft diversion channel outside the exit end of the insertion channel. The first mentioned weft stop motion provides a signal when the inserted weft thread is too short. The second weft stop motion provides a signal when the inserted weft thread is too long.
German Patent Publication DE 3,810,335 A1 (Rupp et al.), discloses an air jet loom with a stretching needle for the weft thread. The stretching needle is positioned in a spacing between the warp threads near the end of the weft insertion channel in the air weaving loom reed.
U.S. Pat. No. 5,735,316 (Hehle), discloses a leading end weft stretcher for an air jet weaving loom. A first weft stop motion device is arranged near the selvage forming portion of the reed to monitor the arrival of a leading end of a weft thread. A stretcher is arranged downstream of the exit end of the weft insertion channel. The stretcher is equipped with its own weft stop motion device. However, the stretcher is not adjustable for different stretching characteristics of the weft thread.
European Patent Publication EP 0,645,485 A1 (Granelli et al.) discloses a stretching device for an air jet weaving loom. The device is positioned at the exit end of the insertion channel and the stretching channel has an arc-shape that returns with its exit end into the extension of the weft insertion channel. At least two weft stop motion devices (7) and (13) are needed.
The above described prior art leaves room for improvement, especially with regard to the simplification of the weft stretcher construction and with regard to the reduction of structural components.